Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Scientists reprogram cancer cells with low doses of epigenetic drugs

23.03.2012
Experimenting with cells in culture, researchers at the Johns Hopkins Kimmel Cancer Center have breathed possible new life into two drugs once considered too toxic for human cancer treatment.

The drugs, azacitidine (AZA) and decitabine (DAC), are epigenetic-targeted drugs and work to correct cancer-causing alterations that modify DNA.

The researchers said the drugs also were found to take aim at a small but dangerous subpopulation of self-renewing cells, sometimes referred to as cancer stem cells, which evade most cancer drugs and cause recurrence and spread.

In a report published in the March 20, 2012, issue of Cancer Cell, the Johns Hopkins team said their study provides evidence that low doses of the drugs tested on cell cultures cause antitumor responses in breast, lung, and colon cancers.

Conventional chemotherapy agents work by indiscriminately poisoning and killing rapidly-dividing cells, including cancer cells, by damaging cellular machinery and DNA. "In contrast, low doses of AZA and DAC may re-activate genes that stop cancer growth without causing immediate cell-killing or DNA damage," says Stephen Baylin, M.D., Ludwig Professor of Oncology and deputy director of the Johns Hopkins Kimmel Cancer Center.

Many cancer experts had abandoned AZA and DAC for the treatment of common cancers, according to the researchers, because they are toxic to normal cells at standard high doses, and there was little research showing how they might work for cancer in general. Baylin and his colleague Cynthia Zahnow, Ph.D., decided to take another look at the drugs after low doses of the drugs showed a benefit in patients with a pre-leukemic disorder called myelodysplastic syndrome (MDS). Johns Hopkins investigators also showed benefit of low doses of the drugs in tests with a small number of advanced lung cancer patients. "This is contrary to the way we usually do things in cancer research," says Baylin, noting that "typically, we start in the laboratory and progress to clinical trials. In this case, we saw results in clinical trials that made us go back to the laboratory to figure out how to move the therapy forward."

For the research, Baylin and Zahnow's team worked with leukemia, breast, and other cancer cell lines and human tumor samples using the lowest possible doses that were effective against the cancers. In all, the investigators studied six leukemia cell lines, seven leukemia patient samples, three breast cancer cell lines, seven breast tumor samples (including four samples of tumors that had spread to the lung), one lung cancer tumor sample, and one colon cancer tumor sample. The team treated cell lines and tumor cells with low-dose AZA and DAC in culture for three days and allowed the drug-treated cells to rest for a week. Treated cells and tumor samples were then transplanted into mice where the researchers observed continued antitumor responses for up to 20 weeks. This extended response was in line with observations in some MDS patients who continued to have anticancer effects long after stopping the drug.

The low-dose therapy reversed cancer cell gene pathways, including those controlling cell cycle, cell repair, cell maturation, cell differentiation, immune cell interaction, and cell death. Effects varied among individual tumor cells, but the scientists generally saw that cancer cells reverted to a more normal state and eventually died. These results were caused, in part, by alteration of the epigenetic, or chemical environment, of DNA. Epigenetic activities turn on certain genes and block others, says Zahnow, assistant professor of oncology and the Evelyn Grolman Glick Scholar at Johns Hopkins.

The research team also tested AZA and DAC's effect on a type of metastatic breast cancer cell thought to drive cancer growth and resist standard therapies. Metastatic cells are difficult to study in standard laboratory tumor models, because they tend to break away from the original tumor and float around in blood and lymph fluids. The Johns Hopkins team re-created the metastatic stem cells' environment, allowing them to grow as floating spheres. "These cells were growing well as spheres in suspension, but when we treated the cells with AZA, both the size and number of spheres were dramatically reduced," says Zahnow.

The precise mechanism of how the drugs work is the focus of ongoing studies by Baylin and his team. "Our findings match evidence from recent clinical trials suggesting that the drugs shrink tumors more slowly over time as they repair altered mechanisms in cells and genes return to normal function and the cells may eventually die," says Baylin.

The results of clinical trials in lung cancer, led by Johns Hopkins' Charles Rudin, M.D., and published late last year in Cancer Discovery, also indicate that the drugs make tumors more responsive to standard anticancer drug treatment. This means, they say, that the drugs could become part of a combined treatment approach rather than a stand-alone therapy and as part of personalized approaches in patients whose cancers fit specific epigenetic and genetic profiles.

Low doses of both drugs are approved by the U.S. Food and Drug Administration for the treatment of MDS and chronic myelomonocytic leukemia (CMML). Clinical trials in breast and lung cancer have begun in patients with advanced disease, and trials in colon cancer are planned.

In addition to Baylin and Zahnow, other investigators participating in this study include Hsing-Chen Tsai, Huili Li, Leander Van Neste, Yi Cai, Carine Robert, Feyruz V. Rassool, James J. Shin, Kirsten M. Harbom, Robert Beaty, Emmanouil Pappou, James Harris, Ray-Whay Chiu Yen, Nita Ahuja, Malcolm V. Brock, Vered Stearns, David Feller-Kopman, Lonny B. Yarmus, Yi-Chun Lin, Alana L. Welm, Jean-Pierre Issa, Il Minn, William Matsui, Yoon-Young Jang, and Saul J. Sharkis.

The research was funded by a SPORE grant for lung cancer from the National Institutes of Health, the Hodson Trust Foundation, Entertainment Industry Foundation, Lee Jeans, Samuel Waxman Cancer Research Foundation, Department of Defense Breast Cancer Research Program, Huntsman Cancer Foundation, and the Cindy Rosencrans Fund for Triple Negative Breast Cancer Research. All of the studies have been accelerated by funding from the Stand Up to Cancer (SU2C) project in partnership with the American Association of Cancer Research (AACR).

On the Web:

Clinical trial of epigenetics therapy published in Cancer Discovery:
http://www.hopkinsmedicine.org/news/media/releases/combination_epigenetic_therapy_clinical_trial_results_
What is epigenetics?
http://www.hopkinsmedicine.org/kimmel_cancer_center/research_clinical_trials/research/su2c/what_is_epigenetics.html
SU2C Epigenetics Dream Team:
http://youtu.be/KgXBrxvlUeA
Stephen Baylin, M.D., explains epigenetics:
http://youtu.be/UW3f2XAxjdM

Vanessa Wasta | EurekAlert!
Further information:
http://www.jhmi.edu

More articles from Life Sciences:

nachricht Nanocages in the lab and in the computer: how DNA-based dendrimers transport nanoparticles
19.10.2018 | University of Vienna

nachricht Less animal experiments on the horizon: Multi-organ chip awarded
19.10.2018 | Fraunhofer-Institut für Werkstoff- und Strahltechnik IWS

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Goodbye, silicon? On the way to new electronic materials with metal-organic networks

Scientists at the Max Planck Institute for Polymer Research (MPI-P) in Mainz (Germany) together with scientists from Dresden, Leipzig, Sofia (Bulgaria) and Madrid (Spain) have now developed and characterized a novel, metal-organic material which displays electrical properties mimicking those of highly crystalline silicon. The material which can easily be fabricated at room temperature could serve as a replacement for expensive conventional inorganic materials used in optoelectronics.

Silicon, a so called semiconductor, is currently widely employed for the development of components such as solar cells, LEDs or computer chips. High purity...

Im Focus: Storage & Transport of highly volatile Gases made safer & cheaper by the use of “Kinetic Trapping"

Augsburg chemists present a new technology for compressing, storing and transporting highly volatile gases in porous frameworks/New prospects for gas-powered vehicles

Storage of highly volatile gases has always been a major technological challenge, not least for use in the automotive sector, for, for example, methane or...

Im Focus: Disrupting crystalline order to restore superfluidity

When we put water in a freezer, water molecules crystallize and form ice. This change from one phase of matter to another is called a phase transition. While this transition, and countless others that occur in nature, typically takes place at the same fixed conditions, such as the freezing point, one can ask how it can be influenced in a controlled way.

We are all familiar with such control of the freezing transition, as it is an essential ingredient in the art of making a sorbet or a slushy. To make a cold...

Im Focus: Micro energy harvesters for the Internet of Things

Fraunhofer IWS Dresden scientists print electronic layers with polymer ink

Thin organic layers provide machines and equipment with new functions. They enable, for example, tiny energy recuperators. In future, these will be installed...

Im Focus: Dynamik einzelner Proteine

Neue Messmethode erlaubt es Forschenden, die Bewegung von Molekülen lange und genau zu verfolgen

Das Zusammenspiel aus Struktur und Dynamik bestimmt die Funktion von Proteinen, den molekularen Werkzeugen der Zelle. Durch Fortschritte in der...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

Conference to pave the way for new therapies

17.10.2018 | Event News

Berlin5GWeek: Private industrial networks and temporary 5G connectivity islands

16.10.2018 | Event News

5th International Conference on Cellular Materials (CellMAT), Scientific Programme online

02.10.2018 | Event News

 
Latest News

Nanocages in the lab and in the computer: how DNA-based dendrimers transport nanoparticles

19.10.2018 | Life Sciences

Thin films from Braunschweig on the way to Mercury

19.10.2018 | Physics and Astronomy

App-App-Hooray! - Innovative Kits for AR Applications

19.10.2018 | Trade Fair News

VideoLinks
Science & Research
Overview of more VideoLinks >>>